CN116670857A - Lithium-nickel-based composite oxides as positive electrode active materials for rechargeable lithium-ion batteries - Google Patents

Abstract

The present invention provides a positive electrode active material powder for a lithium ion rechargeable battery, wherein the positive electrode active material comprises Li, M ', S, and O, wherein M' consists of: -Ni in an amount x between 60.0 and 95.0 mol% relative to M ', co in an amount y between 0.0 and 25.0 mol% relative to M ', mn in an amount z between 0.0 and 25.0 mol% relative to M ', W in an amount a of 0.05 or more mol% relative to M ', D in an amount b between 0.0 and 2.0 mol% relative to M ', wherein D comprises at least one of the following elements: al, B, ba, ca, cr, F, fe, mg, mo, nb, si, sr, ti, Y, V, zn and Zr, and-wherein x, y, z, a and b are measured by ICP, -wherein x+y+z+a+b is 100.0 mole%, wherein the positive electrode active material comprises 0.30 mole% or more of soluble sulfur relative to the M' content.

Description

Lithium-nickel-based composites as positive electrode active materials for rechargeable lithium-ion batteries Synthetic oxides

Technical field and background technology

The present invention relates to a lithium nickel-based oxide positive electrode active material for lithium ion secondary batteries (LIB) suitable for electric vehicle (EV) and hybrid electric vehicle (HEV) applications, which The positive electrode active material powder contains lithium transition metal-based oxide particles containing soluble sulfur also known as sulfate ion (SO ₄ ²⁻ ).

Positive electrode active materials are defined as materials that are electrochemically active in the positive electrode. For active materials, it must be understood that the material is capable of trapping and releasing lithium ions when subjected to a change in voltage over a predetermined period of time.

In particular, the present invention relates to a high nickel-based oxide positive electrode active material (hereinafter referred to as "high Ni compound"), that is, a high Ni compound in which the atomic ratio of Ni to M' is at least 75.0% (or 75.0at%), preferably at least 77.5% (or 77.5at%), more preferably at least 80% (or 80.0at%).

Within the framework of the present invention, at% means atomic percent. at% or "atomic percent" in the expression of a given element of concentration means what percent of all the atoms in the claimed compound are atoms of that element.

The weight percent (wt %) of the first element E in the material (E _wt1 ) can be converted from a given atomic percent (at %) of the first element E in the material (E _at1 ) by applying the following formula: Wherein the product of E _at1 and E _aw1 (E _aw1 is the atomic weight (or molecular weight) of the first element E) divided by the sum of E _ati x E _awi of other elements in the material, n is the number of different elements contained in the material an integer of .

With the development of EVs and HEVs, creating a demand for Li-ion batteries suitable for such applications, high-Ni-based compounds are increasingly being explored as solid candidates for use as positive electrode active materials for LIBs because of their cost Relatively cheap (relative to alternatives such as lithium cobalt-based oxides) and have higher capacity at higher operating voltages.

Such a high-Ni compound is known, for example, from documents JP5584456B2 (hereinafter referred to as "JP'456") or JP5251401B2 (hereinafter referred to as "JP'401").

JP '456 discloses a high Ni compound having a content of SO ₄ ^2- ions (eg sulfate as described in JP '456) at the top of the particles of the high Ni compound in the range of 1000 ppm to 4000 ppm. The calculated molar content of soluble sulfur is in the range of 0.1 mol % to 0.4 mol % relative to the total molar content of Ni, Co and Mn. JP'456 explains that when the amount of sulfate group is within the above range, the capacity retention rate and discharge capacity characteristics of the compound increase. However, if the amount of sulfate radicals is less than the above range, the capacity retention rate decreases, and if the amount exceeds the above range, the discharge capacity decreases.

JP'401 proposes that the application of a sulfate coating (in particular a lithium sulfate coating) on primary particles allows the design of secondary particles resulting from aggregation of said sulfate-coated primary particles with specific pores structure to allow higher cycle durability and higher initial discharge capacity to be imparted to the high Ni compound made of the secondary particles. Furthermore, JP'401 states that this specific pore structure is achieved once the sulfate coating is washed and removed.

Although high-Ni compounds are expected to have the above-mentioned advantages, they also have disadvantages such as reduced cycle stability due to their high Ni content.

As an illustration of these disadvantages, prior art high Ni compounds have a low initial discharge capacity of no more than 180 mAh/g (JP'456) or a limited capacity retention of up to 86% (JP'401).

Currently, there is therefore a need to achieve high Ni compounds with a sufficiently high first discharge capacity (i.e. at least 207 mAh/g), which according to the present invention is used in LIBs suitable for (H)EV applications prerequisites.

An object of the present invention is to provide a positive electrode active material having an improved initial charge capacity of at least 207 mAh/g.

thank you

The present invention was made with the support of the Material/Component Technology Development Program of the Korea Evaluation Industrial Technology Institute funded by the Ministry of Trade, Industry and Energy (MOTIE, Republic of Korea). [Project Name: Development of High Power (High Discharge Rate) Li-ion Secondary Battery with 8C Rate Class / Project Number: 20011287 / Contribution Rate: 100%]

Contents of the invention

This object is achieved by providing a positive electrode active material for lithium ion batteries, wherein the positive electrode active material comprises Li, M', S and O, wherein M' consists of:

- Ni whose content x is between 60.0 mol % and 95.0 mol % relative to M',

- Co, whose content y is between 0.0 mol % and 25.0 mol % relative to M',

- Mn, whose content z is between 0.0 mol % and 25.0 mol % relative to M',

- W whose content a is between 0.05 mol % and 0.50 mol % relative to M',

- D, the content b of which is between 0.0 mol % and 2.0 mol % relative to M', wherein D comprises at least one of the following elements: Al, B, Ba, Ca, Cr, F, Fe, Mg, Mo , Nb, Si, Sr, Ti, Y, V, Zn and Zr, and

- where x, y, z, a and b are measured by ICP,

- where x+y+z+a+b is 100.0 mol %,

wherein the positive electrode active material comprises soluble sulfur in an amount between 0.30 mol % and 2.00 mol % relative to M'.

Note that when it is stated that an element is present in a content between 0.0 mol % and another value, it means that the element may not be present at all, in other words, the element is optional.

Preferably, said soluble sulfur can be associated to SO ₄ ^2- or sulfate form, more precisely to sulfate such as Li ₂ SO ₄ form, as determined by XPS. Soluble sulfur can also associate to SO ₃ ^2- or sulfite forms, more precisely, sulfites.

According to stage A) ICP analysis in the detailed description, the soluble sulfur content is easily determined by ICP analysis after washing the positive electrode active material of the present invention with water.

Within the framework of the present invention, ppm refers to the concentration unit, parts per million, meaning 1 ppm = 0.0001% by weight.

Furthermore, within the framework of the present invention, the term "sulfur" refers to the presence of sulfur atoms or elemental sulfur in the claimed positive electrode active material.

The invention relates to the following embodiments:

Implementation 1

In a first aspect, the present invention relates to a positive electrode active material for a lithium ion battery, wherein said positive electrode active material comprises Li, M', S and O, wherein M' consists of:

- Ni whose content x is between 60.0 mol % and 95.0 mol % relative to M',

- Co, whose content y is between 0.0 mol % and 25.0 mol % relative to M',

- Mn, whose content z is between 0.0 mol % and 25.0 mol % relative to M',

-W, the content a of which is 0.05 mol% or more relative to M',

- D, the content b of which is between 0.0 mol % and 2.0 mol % relative to M', wherein D comprises at least one of the following elements: Al, B, Ba, Ca, Cr, F, Fe, Mg, Mo , Nb, Si, Sr, Ti, Y, V, Zn and Zr, and

- where x, y, z, a and b are measured by ICP,

- where x+y+z+a+b is 100.0 mol %,

wherein the positive electrode active material contains soluble sulfur in an amount of 0.30 mol % or more relative to M' content.

Preferably, the positive electrode active material comprises soluble sulfur in an amount between 0.30 mol % and 2.00 mol % relative to M'.

Preferably, soluble sulfur is present in the positive electrode material in a content of between 0.50 mol % and 1.50 mol % relative to M'. More preferably, between 0.50 mol % and 1.00 mol % with respect to M'.

Preferably, the soluble sulfur content is equal to the reduction in S content relative to M' as determined by ICP after contacting the positive electrode active material powder with deionized water several times at 25°C (or dispersing into deionized water) For at least 5 minutes (by stirring), the positive electrode active material powder is filtered, and the positive electrode active material powder is dried.

In a preferred embodiment, said Ni is present in a content x of 75 mol % or more, and preferably at least 80 mol %.

In a preferred embodiment, said Ni is present in a content x of 90 mol % or less.

In a preferred embodiment, the Co is present in a content y of 5.0 mol % or more.

In a preferred embodiment, the Co is present in a content y of 10.0 mole % or less.

In a preferred embodiment, said Ni is present in a content x of 75 mol % or more, and preferably at least 80 mol %.

Preferably, a is at most 0.50 mol%.

In a preferred embodiment, the content a of W relative to M' is between 0.05 mol % and 0.50 mol %.

In another embodiment, the content a of W is between 0.10 mol % and 0.30 mol % relative to M'.

Embodiment 2

In a second embodiment, preferably according to embodiment 1, said positive electrode active material comprises Al in an amount between 0.10 mol % and 1.00 mol % relative to M'.

Preferably, said positive electrode active material comprises an Al content of between 0.20 mol % and 0.50 mol % relative to M'.

Preferably, the positive electrode active material contains 0.10 mol % or more, and preferably 0.20 mol % or more of Al relative to the M' content.

Preferably, the positive electrode active material contains Al at most 1.0 mol %, and preferably at most 0.50 mol %, relative to the M' content.

For completeness, it is emphasized that Al is included in D, so that said Al content is included in said parameter b.

Thus, in other words, in a preferred embodiment, D comprises Al at most 1.0 mol %, and preferably at most 0.50 mol %, relative to M'.

In addition, in a preferred embodiment, D includes Al in an amount of 0.10 mol % or more, and preferably 0.20 mol % or more, relative to M'.

Embodiment 3

In a third embodiment, preferably according to embodiments 1 to 2, the positive electrode active material comprises B in an amount between 0.05 mol % and 1.50 mol % relative to M'.

Preferably, the positive electrode active material comprises a B content of at least 0.05 mol %, and more preferably at least 0.1 mol %, relative to the M' content.

Preferably, the positive electrode active material comprises at most 1.5 mol %, and preferably at most 1.0 mol %, of B relative to the M' content.

For completeness, it is emphasized that B is included in D, so that said B content is included in said parameter b.

Thus, in other words, in a preferred embodiment D comprises a content of at most 1.5 mole %, more preferably at most 1.0 mole %, and even more preferably at most 0.50 mole % of B relative to M'.

In addition, in a preferred embodiment, D includes B in an amount of 0.05 mol % or more, and preferably 0.10 mol % or more, relative to M'.

Embodiment 4

In a third embodiment, preferably according to embodiments 1 to 3, said material has:

- S content S _A and W content W _A , where S _A and W _A are determined by ICP analysis, where S _A and W _A are expressed as mole fractions compared to the sum of x and y and z,

- mean S fraction S _B and mean W fraction W _B , where S _B and W _B are determined by XPS analysis, where S _B and W _B are expressed as compared to the sum of the fractions of Co, Mn and Ni measured by XPS analysis mole fraction,

- where the ratio S _B /S _A >1.0,

- where the ratio W _B /W _A >1.0.

Preferably, the ratio S _B /S _A is at least 1.5 and at most 600, and more preferably, the ratio W _B /W _A is at least 1.5 and at most 700.

Preferably, the ratio S _B /S _A is at least 50 and at most 550, and more preferably S _B /S _A is at least 100 and at most 500.

Preferably, the ratio W _B /W _A is at least 50 and at most 700, and more preferably W _B /W _A is at least 100 and at most 650.

Note that S _B and S _A refer to the total sulfur content and therefore include soluble sulfur content.

Embodiment 5

In a fifth embodiment, preferably according to embodiments 1 to 4, the material has:

- Al content _AlA , where _AlA is determined by ICP analysis, where _AlA is expressed as mole fraction compared to the sum of x and y and z,

- the average Al fraction _AlB , where _AlB is determined by XPS analysis, where _AlB is expressed as a mole fraction compared to the sum of the fractions of Co, Mn and Ni measured by XPS analysis,

- where the ratio Al _B /Al _A >1.0.

Preferably, the ratio Al _B /Al _A is at least 3.0 and at most 2500.

Preferably, the ratio Al _B /Al _A is at least 200 and at most 2400, and more preferably Al _B /Al _A is at least 300 and at most 2300.

Embodiment 6

In a sixth embodiment, preferably according to embodiments 1 to 5, the material has:

- B content _BA , where _BA is determined by ICP analysis, where _BA is expressed as mole fraction compared to the sum of x and y and z,

- mean B fraction B _B , where B _B is determined by XPS analysis, where B _B is expressed as mole fraction compared to the sum of the fractions of Co, Mn and Ni measured by XPS analysis,

- where the ratio B _B /B _A >1.0.

Preferably, the ratio B _B /B _A is at least 100 and at most 1500.

Preferably, the ratio B _B /B _A is at least 200 and at most 1400, and more preferably B _B /B _A is at least 300 and at most 1200.

In particular, for any one of Embodiments 1 to 6, S _B , W _B , Al _B and B _B are the average fractions of S, W, Al and B, respectively, which are present in the particles of the positive electrode material powder according to the present invention measured in a region defined between a first point on the outer edge of the particle and a second point at a distance from the first point, separating the first point from the second point The distance of is equal to the penetration depth of the XPS, the penetration depth D being comprised between 1.0 and 10.0 nm. In particular, the penetration depth is the distance along an axis perpendicular to an imaginary line tangent to said outer edge and passing through said first point.

In the framework of the invention, the outer edge of a particle is the boundary or outer limit that distinguishes the particle from its outer environment.

The present invention relates to the use of the positive electrode active material according to any one of the preceding embodiments 1 to 6 in a battery.

The present invention also includes a method for manufacturing the positive electrode active material according to any one of the foregoing embodiments 1 to 6, the method comprising the steps of:

- preparation of a first sintered lithium transition metal-based oxide compound,

- combining said first sintered lithium transition metal-based oxide compound with a source of tungsten, preferably with WO ₃ , a source of sulfate ions, preferably with Al ₂ (SO ₄ ) ₃ and/or H ₂ SO ₄ , and with water mixed to obtain a mixture, and

- heating the mixture in an oxidizing atmosphere in a furnace at a temperature of 350°C to less than 500°C, preferably at most 450°C, for a period of 1 hour to 20 hours in order to obtain the positive electrode active material powder according to the invention.

Preferably, the lithium metal- _based oxide compound is mixed with a source of boron, preferably _H3BO3 , and a source of tungsten and a source of sulfate ions.

Description of drawings

Figure 1. SEM image of EX1.3

Figure 2a. XPS spectrum of Al2p and Ni3p peaks of EX1.4

Figure 2b. XPS spectrum of the S2p peak of EX1.4

Figure 2c. XPS spectrum of W2f peak of EX1.4

Figure 2d. XPS spectrum of the Bls peak of EX3

Detailed ways

In the drawings and in the following detailed description, preferred embodiments are described in detail to enable the practice of the invention. Although the invention has been described with reference to these specific preferred embodiments, it is to be understood that the invention is not limited to these preferred embodiments. The invention encompasses numerous alternatives, modifications and equivalents, which will become apparent from consideration of the following detailed description and accompanying drawings.

A) ICP analysis

Al) ICP measurement

Li, Ni, Mn, Co, Al, B, W, and S contents of the positive electrode active material powder were measured by an inductively coupled plasma (ICP) method using Agilent ICP720-ES. A 2 g sample of the product powder was dissolved in 10 ml of high-purity hydrochloric acid in an Erlenmeyer flask. The vial can be covered with a glass slide and heated on a 380°C hot plate until the precursor is completely dissolved. After cooling to room temperature, the solution in the Erlenmeyer flask was poured into a 250mL volumetric flask. Afterwards, fill the volumetric flask with deionized water up to the 250 mL mark and then homogenize completely. An appropriate amount of solution was removed by pipette and transferred to a 250 mL volumetric flask for a second dilution, at which point the flask was filled with internal standard and 10% hydrochloric acid to the 250 mL mark and then homogenized. Finally, this 50 mL solution was used for ICP measurement.

A2) Soluble sulfur measurement

In order to investigate the soluble S content in the lithium transition metal-based oxide particles according to the present invention, washing and filtering processes were performed. 5 g of positive electrode active material powder and 100 g of ultrapure water were weighed out in a beaker. The electrode active material powder was dispersed in water at 25° C. for 5 minutes using a magnetic stirrer. The dispersion was vacuum filtered and the dried powder was analyzed by ICP measurement as described above to determine the amount of soluble S-containing compound.

B) X-ray photoelectron spectroscopy analysis

In the present invention, X-ray photoelectron spectroscopy (XPS) is used to analyze the surface of the positive electrode active material powder particles. In XPS measurements, signals are collected from the first few nanometers (eg, 1 nm to 10 nm) of the uppermost part of the sample (ie, the surface layer). Therefore, all elements measured by XPS are contained in the surface layer.

For the surface analysis of the positive electrode active material powder particles, XPS measurements were performed using a Thermo K-α+ spectrometer (ThermoScientific, https://www.thermofisher.com/order/catalog/product/IQLAADGAAFFACVMAHV).

Monochromatic Al Ko radiation (hu = 1486.6 eV) was used with a spot size of 400 μm and a measurement angle of 45°. A wide-range measurement scan was performed at a pass energy of 200 eV to identify elements present at the surface. The CIs peak with maximum intensity (or centered) at a binding energy of 284.8 eV was used as the calibrated peak position after data collection. At least 10 precise narrow-range scans were then performed at 50 eV for each identified element to determine the precise surface composition.

Curve fitting was performed with CasaXPS version 2.3.19PR1.0 (Casa Software, http://www.casaxps.com/) using Shirley-type background processing and Scofield sensitivity factors. Fitting parameters conform to Table 1a. Line shape GL(30) is a Gauss/Lorentz product formula with 70% Gaussian lines and 30% Lorentzian lines. LA(α,β,m) is an asymmetric line shape, where α and β define the tail extension of the peak, and m defines the width.

Table 1a. XPS fit parameters for Ni2p3, Mn2p3, Co2p3, Al2p, S2p, W4f and B1s .

For Al, S, Co and W peaks, constraints were set for each defined peak according to Table 1b. Ni3p (including Ni3p3, Ni3pl, Ni3p3 satellites and Ni3pl satellites) and W5p3 were not quantified.

Table 1b. XPS fit constraints for peak fitting .

The surface contents of Al, S, B, and W determined by XPS are expressed as mole fractions of Al, S, B, and W in the particle surface layer divided by the total content of Ni, Mn, and Co in the surface layer, respectively.

It is calculated as follows:

Fraction of Al = Al _B = Al (atomic %)/(Ni (atomic %) + Mn (atomic %) + Co (atomic %))

Fraction of S = S _B = S (atomic %)/(Ni (atomic %) + Mn (atomic %) + Co (atomic %))

Fraction of W = W _B = W (atomic %)/(Ni (atomic %) + Mn (atomic %) + Co (atomic %))

Fraction of B = B _B = B (atomic %)/(Ni (atomic %) + Mn (atomic %) + Co (atomic %))

Information on XPS peak positions can be readily obtained in the field and composition report specifications after fitting. The XPS plots of Al, S, W and B are shown in Figures 2a, 2b, 2c and 2d, respectively.

C) Button battery test

C1) button battery preparation

To prepare the positive electrode, a slurry (formula 96.5:1.5:2.0 by weight) containing positive electrode active material powder, conductor (Super P, Timcal), binder (KF#9305, Kureha) was mixed in a solvent (NMP , Mitsubishi) with a high-speed homogenizer. Spread the homogenized slurry on one side of the aluminum foil using a knife coater with a gap of 170 μm. The slurry coated foil was dried in an oven at 120°C and then pressed using a calendering tool. It was then dried again in a vacuum oven to completely remove the remaining solvent in the electrode film. Coin cells were assembled in an argon-filled glove box. A separator (Celgard 2320) was placed between the positive electrode and a lithium foil used as the negative electrode. EC/DMC (1:2) containing IM LiPF ₆ was used as the electrolyte and was dropped between the separator and the electrodes. Then, the coin cell is completely sealed to prevent electrolyte leakage.

C2) Test method

The test method is the traditional "constant cut-off voltage" test. The conventional coin cell testing in this invention followed the schedule shown in Table 2. Each cell was cycled at 25°C using a Toscat-3100 computer controlled constant current cycling station (from Toyo). A 1C current definition of 220mA/g is planned to be used. The initial charge capacity (CQ1) and discharge capacity (DQ1) were measured at a C-rate of 0.1C in the constant current mode (CC) from 4.3V to 3.0V/Li metal window.

The irreversible capacity IRRQ is expressed in % as follows:

Table 2. Cycle Schedule for Coin Cell Test Method

The present invention is further illustrated by the following examples:

Comparative example 1

The high-Ni compound CEX1 with the formula Li _1+d (Ni _0.80 Mn _0.10 Co _0.10 ) _id O ₂ was obtained by a double sintering process, which is a solid-state reaction between a lithium source and a transition metal-based source, which operates as follows:

1) Co-precipitation: In a large continuous stirred tank reactor (CSTR) with mixed nickel manganese cobalt sulfate, sodium hydroxide and ammonia, the metal composition is Ni _0.80 Mn _0.10 Co _0.10 .io Hydroxide precursors for transition metal-based oxidations.

2) Blending: The transition metal-based hydroxide and LiOH as a lithium source were uniformly blended in an industrial blending device at a ratio of lithium to metal M′ (Li/M′) of 1.01.

3) The first sintering: the blend was sintered at 730° C. for 12 hours in an oxygen-containing atmosphere. The sintered powder is crushed, classified and sieved in order to obtain a sintered intermediate product.

4) Second sintering: the intermediate product was sintered at 830° C. for 12 hours in an oxygen-containing atmosphere, so as to obtain a sintered powder of aggregated primary particles. The sintered powder was crushed, classified and sieved in order to obtain CEX1 of the formula Li _1.005 M' _0.995 O ₂ (d=0.005), where M'=Ni _0.80 Mn _0.10 Co _0.10 . CEX1 has a D50 of 12.0 μm and a span of 1.24. CEX1 contains trace amounts of sulfur obtained from the metal sulfate source in step 1) co-precipitation process.

Optionally, the dopant source can be added together with the lithium source in the co-precipitation process in step 1) or in the blending step in step 2). For example, dopants may be added to improve the electrochemical characteristics of the positive electrode active material powder product.

CEX1.1 is not in accordance with the invention.

CEX1.2 not according to the invention was prepared by the following procedure:

Step 1) Wet mixing: CEX1.1 is mixed with an aluminum sulfate solution obtained by dissolving 1000 ppm of Al from _Al2 ( _SO4 ) ₃ powder to 3.5% by weight relative to the weight of CEX1.1 prepared in deionized water.

Step 2) Heating: The mixture obtained from step 1) was heated at 385° C. for 8 hours under an oxygen atmosphere, then ground and sieved in order to obtain CEX1.2 containing about 1000 ppm Al relative to the total weight of EX1.2.

Example 1

EX1.1 according to the invention was prepared by the following procedure: Step 1) Dry blending: CEX1.1 was dry blended with 2000 ppm of W from WO ₃ powder in order to obtain a dry mixture.

Step 2) Wet mixing: the dry mixture obtained from step 1) is mixed with an aluminum sulphate solution by dissolving 600 ppm of Al obtained from _Al2 ( _SO4 ) ₃ powder relative to CEX1.1 was prepared in 3.5% by weight deionized water.

Step 3) Heating: The wet mixture obtained from step 2) was heated at 385° C. for 8 hours under an oxygen atmosphere, followed by grinding and sieving to obtain EX1.2.

EX1.2 according to the invention was prepared according to the same method as EX1.1, except that 3000 ppm W was added in step 1).

EX1.3 according to the invention was prepared according to the same method as EX1.1, except that 4000 ppm W was added in step 1). Take the SEM image of EX1.3, see Figure 1.

EX1.4 according to the invention was prepared according to the same method as EX1.1, except that 800 ppm Al was added in step 2).

EX1.5 according to the invention was prepared according to the same method as EX1.4, except that 3000 ppm W was added in step 1).

EX1.6 according to the invention was prepared according to the same method as EX1.4, except that 4000 ppm W was added in step 1).

Example 2

EX2 according to the invention was prepared by the following procedure: Step 1) Dry blending: CEX1.1 was dry blended with 4500 ppm W from WO ₃ powder in order to obtain a dry blend.

Step 2) Wet mixing: the dry mixture from step 1) is mixed with 0.5 mol% S from a sulfuric acid solution dissolved by dissolving a concentrated _H2SO4 solution (98% concentration) in order to obtain _a wet mixture Prepared in 3.5% by weight deionized water relative to the weight of CEX1.1.

Step 3) Heating: The wet mixture obtained from step 2) was heated at 285° C. for 8 hours under an oxygen atmosphere, followed by grinding and sieving to obtain EX1.2.

Comparative example 2

CEX2 not according to the invention was prepared according to the same method as EX2, except that the wet mixing step 2) was omitted.

Example 3

EX3 according to the invention was prepared by the _following procedure: Step 1) Dry blending: CEX1.1 was dry blended with 500 ppm B from _H3BO3 and 4500 ppm W from _WO3 powder to obtain a dry mixture.

Step 2) Wet mixing: The dry mix from step 1) was mixed with an aluminum sulfate solution by dissolving 1000 ppm of Al from _Al2 ( _SO4 ) ₃ powder to a weight relative to the dry mix of 3.5% by weight deionized water.

Step 3) Heating: The wet mixture obtained from step 2) was heated at 385° C. for 8 hours under an oxygen atmosphere, followed by grinding and sieving to obtain EX3.

Table 3. Summary of the compositions and corresponding electrochemical properties of the examples and comparative examples .

*relative to the molar content of Ni, Mn, Co, Al and W

Table 4. XPS analysis results and ratios analyzed by ICP for CEX1.2, EX1.4 and EX3

**M: Molar content of a specific element relative to the molar content of Ni, Mn and Co

Table 5. XPS peak positions of CEX1.2, EX1.4 and EX3

Table 3 summarizes the Al, W and soluble S compositions and their corresponding electrochemical properties in Examples and Comparative Examples. EX1.1 to EX1.6 and EX2 comprising W in an amount between 0.05 mol % and 0.50 mol % relative to M' and soluble S in an amount between 0.30 mol % and 2.00 mol % relative to M' can achieve this It is an object of the invention to provide a positive electrode active material having an improved initial charge capacity of at least 207 mAh/g. In addition, EX3 also contains 0.4 mol% B, which further improves the electrochemical properties.

Table 4 summarizes the XPS analysis results of CEX1.2, EX1.4 and EX3, showing the atomic ratios of Al, S, B and W relative to the total atomic fractions of Ni, Mn and Co. The table also compares the results with those of the ICP. An atomic ratio higher than 0 indicates that the Al, S, B, and W are present in the surface of the positive electrode active material in association with XPS measurements whose signals are obtained from the front of the uppermost part of the sample (i.e., the surface layer). A few nanometers (eg, 1 nm to 10 nm) are obtained. On the other hand, the atomic ratios of Al, S, B, and W measured by ICP are from the whole particle. Therefore, a ratio of XPS to ICP higher than 1 indicates that the element Al, S, B or W is mainly present on the surface of the positive electrode active material. XPS to ICP ratios higher than 1 were observed for Al, S and W in EX1.4. Similarly, XPS to ICP ratios higher than 1 were observed for Al, S, B and W in EX3.

Table 5 shows the positions of Al2p, S2p3, W4f7 and Bls XPS peaks of CEX1.2, EX1.4 and EX3 obtained according to the XPS analysis description of the present invention.

Claims (28)

1. A positive electrode active material powder for a lithium ion rechargeable battery, wherein the positive electrode active material comprises Li, S, M ', and O, wherein M' consists of:

ni, ni content x being between 60.0 and 95.0 mol% relative to M',

co, co content y being between 0.0 and 25.0 mol% relative to M',

mn, mn content z being between 0.0 and 25.0 mol% relative to M',

w, W content a is 0.05 mol% or more relative to M',

-D, D content b is between 0.0 and 2.0 mol% with respect to M', wherein D comprises at least one of the following elements: al, B, ba, ca, cr, F, fe, mg, mo, nb, si, sr, ti, Y, V, zn and Zr, and

wherein x, y, z, a and b are measured by ICP,

wherein x+y+z+a+b is 100.0 mol%,

wherein the positive electrode active material contains 0.30 mol% or more of soluble sulfur with respect to the M' content.

2. The positive electrode active material according to claim 1, wherein the content of soluble sulfur is equal to a decrease in S content relative to M' as determined by ICP after: dispersing the positive electrode active material powder into deionized water to obtain a solution, stirring the solution at 25 ℃ for at least 5 minutes, filtering the positive electrode active material powder, and drying the positive electrode active material powder.

3. The positive electrode active material according to any one of the preceding claims, wherein x is between 75 and 90 mole%.

4. The positive electrode active material according to any one of the preceding claims, wherein the content of the soluble sulfur is 0.50 mol% or more with respect to M'.

5. The positive electrode active material according to any one of the preceding claims, wherein a is 0.10 mol% or more.

6. The positive electrode active material according to any one of the preceding claims, wherein the positive electrode active material contains 0.10 mol% or more, and preferably 0.20 mol% or more of Al with respect to the M' content.

7. The positive electrode active material according to any one of the preceding claims, wherein the positive electrode active material comprises at most 1.0 mol% and preferably at most 0.50 mol% Al with respect to the M' content.

8. The positive electrode active material according to any one of the preceding claims, wherein the positive electrode active material comprises at least 0.05 mol% and preferably at least 0.1 mol% B with respect to the M' content.

9. The positive electrode active material according to any one of the preceding claims, wherein the positive electrode active material comprises at most 1.5 mol% and preferably at most 1.0 mol% B relative to the M' content.

10. The positive electrode active material according to any one of the preceding claims, the material having:

s content S _A And W content W _A Wherein S is _A And W is _A Is determined by ICP analysis, wherein S _A And W is _A Expressed as mole fractions compared to the sum of x and y and z,

average S score S _B And average W fraction W _B Wherein S is _B And W is _B Is determined by XPS analysis, wherein S _B And W is _B Expressed as mole fraction compared to the sum of the fractions of Co, mn and Ni measured by XPS analysis,

-wherein the ratio S _B /S _A >1.0，

-wherein the ratio W _B /W _A >1.0。

11. The positive electrode active material according to claim 10, wherein the ratio S _B /S _A At least 1.5.

12. -positive electrode active material according to claims 10 to 11, wherein the ratio W _B /W _A At least 1.5.

13. The positive electrode active material according to any one of claims 10 to 12, wherein the ratio S _B /S _A Up to 600.

14. -positive electrode active material according to any one of claims 10 to 13, wherein the ratio W _B /W _A At most 700.

15. The positive electrode active material according to any one of the preceding claims, the material having:

al content Al _A Wherein Al is _A Is determined by ICP analysis, wherein Al _A Expressed as mole fractions compared to the sum of x and y and z,

average Al fraction Al _B Wherein Al is _B Is determined by XPS analysis in which Al _B Expressed as mole fraction compared to the sum of the fractions of Co, mn and Ni measured by XPS analysis,

-wherein the ratio Al _B /Al _A >1.0。

16. The positive electrode active material according to claim 15, wherein the ratio Al _B /Al _A At least 3.0.

17. The positive electrode active material according to claim 15 to 16, wherein the ratio Al _B /Al _A Up to 2400.

18. The positive electrode active material according to any one of the preceding claims, wherein the positive electrode active material comprises 2.00 mol% or less of the soluble sulfur relative to an M' content.

19. -the positive electrode active material according to any one of the preceding claims, wherein the positive electrode active material comprises 1.00 mol% or less of the soluble sulfur relative to the M' content.

20. The positive electrode active material according to any one of the preceding claims, wherein a is 0.50 mol% or less, and preferably 0.30 mol% or less.

21. -positive electrode active material according to any one of the preceding claims, wherein y is between 5 and 10 mol% with respect to M'.

22. The positive electrode active material according to any one of the preceding claims, the material having:

-B content B _A Wherein B is _A Is determined by ICP analysis, wherein B _A Expressed as mole fractions compared to the sum of x and y and z,

average B score B _B Wherein B is _B Is determined by XPS analysis, wherein B _B Expressed as mole fraction compared to the sum of the fractions of Co, mn and Ni measured by XPS analysis,

-wherein ratio B _B /B _A >1.0。

23. The positive electrode active material according to claim 22, wherein ratio B _B /B _A At least 100.

24. The positive electrode active material according to claims 22 to 23, wherein a ratio B _B /B _A At most 1500.

25. A method for manufacturing the positive electrode active material according to any one of the preceding claims, the method comprising the following successive steps:

preparing a first sintered lithium transition metal-based oxide compound,

-materializing said first sintered lithium transition metal-based oxideThe compound is combined with a tungsten source, preferably with WO ₃ A source of sulfate ions, preferably with Al ₂ (SO ₄ ) ₃ And/or H ₂ SO ₄ And mixing with water to obtain a mixture, and

-heating said mixture in an oxidizing atmosphere in a furnace at a temperature of 350 ℃ to less than 500 ℃, preferably at most 450 ℃ for a time of 1 to 20 hours in order to obtain a positive electrode active material powder according to the invention.

26. The method according to claim 25, wherein a lithium metal based oxide compound is mixed with a boron source and a tungsten source and a sulfate ion source, wherein preferably the boron source is H ₃ BO ₃ 。

27. A battery comprising the positive electrode active material according to any one of claims 1 to 24.

28. Use of the battery of claim 27 in an electric vehicle or a hybrid electric vehicle.